If you're thumbing for max-d, a champ firebird is your best bet. I have a champ bird that has 3 years of service. It's beat, but still flies fairly true to FB flight. That being said, I carry 4 different FBs plus a xXx for OH duties. Unless your throwing into asphalt or rocks, the champ plastic should be good. I know you're asking for vibram - never thrown a vibram OH. Summit is my understable driving putter, and the unlace is my go to for BH drives.

The Flick is the best disc for upside down shots. The Firebird can't compare. All the FB has is overstability. The Flick has a shape that gives it more lift (or less negative lift) upside down=more distance.

Nuke OS or something similarly warp speed and stupidly overstable also go forever. But the smaller rim on the Flick is nice.

depends on what youre looking for. More overstable will have more left to right movement in flight should go farther, understable discs have less left to right. Obviously changing release angles and what not can negate that.
I generally use a XXX for most OH shots, but also use a teebird and occasionally a patriot. I prefer the small rim of the speed 6-9 discs for them

I do keep coming across the Flick as the go to overhand throw. As for the Accent I have not had a chance to throw it, is it overstable, understable? And what is your end goal for your OH?

Thanks birdman101 for the overview on OH and stability. I am still new to OH and learning more about how stability and release effect what the disc will do. Maybe my notes might help. I just might need an insight on these disc and there specs and why they do what they do.

All thrown OH and generally at a vertical release. By basic understanding of stability is understable=turns quicker and shorter overstable=turns later more distance.
Blizzard Champ Boss - turns over very quick and then dives hard left or right based on Thumber or Tomahawk
Beat up DX Valkyrie - turnover quick, short distance. Can throw around obstacles if released at 45 deg.
Champ Tee bird - haven't throw enough yet to understand OH
Champ Banshee - slower turnover, glides to ground upside down. Using this for "pancake" shots. Got an amazing shot when it pancaked off a concrete path last week
DX Viper - Straight up, straight down. Very accurate for attack
Left to figure out - DX Shark, DX Beast, Star Echo Mako, and Classic ROC.

The Flick is the best disc for upside down shots. The Firebird can't compare. All the FB has is overstability. The Flick has a shape that gives it more lift (or less negative lift) upside down=more distance.

Nuke OS or something similarly warp speed and stupidly overstable also go forever. But the smaller rim on the Flick is nice.

MIght depend on the firebird. I had a metleflake champ with a super flat top that was way better for thumbers than the normal champ fb.